alot of guys are kind of confused about the whole offset thing with positive and negative offset. hopefully this can help guys out from now on
The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.
ZERO OFFSET
The hub mounting surface is even with the centerline of the wheel.
POSITIVE OFFSET
The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.
NEGATIVE OFFSET
The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.
MEASURING OFFSET
To determine the offset, the wheel must be measured accurately using the following steps:
1) measure the overall rim width of the wheel.
2) measure the backspace, which is the measurement from the hub surface contact area to the outside of the inner rim.
3) divide the overall rim width by 2 which gives you the center line.
4) subtract the center line (overall rim width divided by 2) from the backspace.
5) a negative answer means the wheel has a negative offset and a positive answer means the wheel has a positive offset